Unease in Hawaii’s Cornfields

WAIMEA, Hawaii — The balmy tropical isles here seem worlds apart from the expansive cornfields of the Midwest, but Hawaii has become the latest battleground in the fight over genetically modified crops.

The state has become a hub for the development of genetically engineered corn and other crops that are sold to farmers around the globe. Monsanto and other seed companies have moved here en masse, and corn now sprouts on thousands of acres where sugar cane or pineapples once grew.

But activists opposed to biotech crops have joined with residents who say the corn farms expose them to dust and pesticides, and they are trying to drive the companies away, or at least rein them in...